Memory cell with top electrode via

ABSTRACT

The present disclosure relates to an integrated chip. The integrated chip includes a memory device surrounded by a dielectric structure disposed over a substrate. The memory device includes a data storage structure disposed between a bottom electrode and a top electrode. A top electrode via couples the top electrode to an upper interconnect wire. A first line is tangent to a first outermost sidewall of the top electrode via and a second line is tangent to an opposing second outermost sidewall of the top electrode via. The first line is oriented at a first angle with respect to a horizontal plane that is parallel to an upper surface of the substrate and the second line is oriented at a second angle with respect to the horizontal plane. The second angle is less than the first angle.

REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation of U.S. application Ser. No.16/416,555, filed on May 20, 2019, which claims the benefit of U.S.Provisional Application No. 62/702,581, filed on Jul. 24, 2018. Thecontents of the above-referenced Patent Applications are herebyincorporated by reference in their entirety.

BACKGROUND

Many modern day electronic devices contain electronic memory configuredto store data. Electronic memory may be volatile memory or non-volatilememory. Volatile memory stores data while it is powered, whilenon-volatile memory is able to store data when power is removed.Magnetic random-access memory (MRAM) devices are one promising candidatefor a next generation non-volatile memory technology.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a cross-sectional view of some embodiments of anintegrated chip having a magnetoresistive random access memory (MRAM)cell comprising a top electrode via with a smaller width than anunderlying bottom electrode via.

FIGS. 2A-2B illustrate some embodiments of an integrated chip having anMRAM cell comprising a top electrode via with a smaller width than anunderlying bottom electrode via.

FIGS. 3-6 illustrates additional cross-sectional views of someembodiments of an integrated chip having an MRAM cell comprising a topelectrode via with a smaller width than an underlying bottom electrodevia.

FIGS. 7-26 illustrate cross-sectional views of some embodiments of amethod of forming an integrated chip having an MRAM cell comprising atop electrode via with a smaller width than an underlying bottomelectrode via.

FIG. 27 illustrates a flow diagram of some embodiments of a method offorming an integrated chip having an MRAM cell comprising a topelectrode via with a smaller width than an underlying bottom electrodevia.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Magnetoresistive random-access memory (MRAM) devices comprise a magnetictunnel junction (MTJ) vertically arranged within a back-end-of-the-line(BEOL) metal stack between a bottom electrode and a top electrode. TheMTJ comprises a pinned layer and a free layer, which are verticallyseparated by a tunnel barrier layer. The magnetic orientation of thepinned layer is static (i.e., fixed), while a magnetic orientation ofthe free layer is capable of switching between a parallel configurationand an anti-parallel configuration with respect to that of the pinnedmagnetic layer. The parallel configuration provides for a low resistancestate that digitally stores data as a first data state (e.g., a logical“0”). The anti-parallel configuration provides for a high resistancestate that digitally stores data as a second data state (e.g., a logical“1”).

The top electrode of an MRAM device is generally connected to anoverlying interconnect wire by way of a top electrode via. The topelectrode via may be formed by etching a via hole into an inter-leveldielectric (ILD) layer over the top electrode and subsequently fillingthe via hole with a conductive material. The via hole may be etchedaccording to a patterned masking layer, such that a size of a topelectrode via is generally defined by characteristics of aphotolithography system. It has been appreciated that a top electrodevia having a relatively small size is easier to land on the topelectrode. It has also been appreciated that if the top electrode via istoo large, the via hole may extend over sides of the top electrode. Dueto etching selectivity between the top electrode and surroundingdielectric layers, a subsequently formed top electrode via can contactan MTJ under the top electrode, leading to shorting of the MTJ andfailure of the MRAM device.

Because the size of a top electrode via is relatively small, the topelectrode via is generally produced as a feature with a greatestprecision on a photomask (e.g., a minimum feature size of a photomask).However, because of this, the top electrode via is subject to criticaldimension (CD) tolerances (e.g., a maximum allowed deviation in sizefrom a target of a feature). As the size of MRAM cells continue todecrease, the CD tolerance of the bottom of the top electrode vias alsoincreases and makes landing the top electrode via on an underlying topelectrode increasingly difficult. The increasing difficulty in landingthe top electrode via on the top electrode can lead to over-etching thatcan cause device failure and reduced yield.

The present disclosure, in some embodiments, relates to an integratedchip having an MRAM cell comprising a top electrode via with a size thatis smaller than a minimum feature size defined by a characteristics of aphotolithography system, and an associated method of formation. Theintegrated chip may comprise a magnetoresistive random access memory(MRAM) device surrounded by a dielectric structure disposed over asubstrate. The MRAM device comprises a magnetic tunnel junction betweena bottom electrode and a top electrode. A bottom electrode via couplesthe bottom electrode to an underlying conductive interconnect wire. Atop electrode via couples the top electrode to an overlying interconnectwire. A bottom surface of the top electrode via has a smaller width thana bottom surface of the bottom electrode via. The smaller width of thebottom surface of the top electrode via allows for the top electrode viato more easily land on the top electrode during fabrication of the MRAMdevice, thereby preventing over-etching that can cause damage to theMRAM device.

FIG. 1 illustrates a cross-sectional view of some embodiments of anintegrated chip 100 having a magnetoresistive random-access memory(MRAM) cell with a top electrode via having a smaller width than anunderlying bottom electrode via.

The integrated chip 100 comprises a magnetoresistive random accessmemory (MRAM) device 111 disposed within a dielectric structure 104 overa substrate 102. The MRAM device 111 comprises a magnetic tunneljunction (MTJ) 114 disposed between a bottom electrode 112 and a topelectrode 116. The MRAM device 111 is configured to store a data statebased upon a resistive value of the MRAM device 111. For example, theMRAM device 111 will either store a first data state (e.g., a logical“0”) if the MRAM device 111 has a low resistance state or a second datastate (e.g., a logical “1”) if the MRAM device 111 has a high resistancestate. During operation, the MTJ 114 can be changed between the lowerresistance state and the high resistance state through the tunnelmagnetoresistance (TMR) effect.

A bottom electrode via 110 is arranged below the MRAM device 111. Thebottom electrode via 110 is configured to couple the MRAM device 111 toone or more lower interconnect layers 106 disposed within the dielectricstructure 104 between the MRAM device 111 and the substrate 102. In someembodiments, the one or more lower interconnect layers 106 may comprisea conductive contact 107, and alternating layers of interconnect vias108 and interconnect wires 109. The one or more lower interconnectlayers 106 are further coupled to an access device 103 arranged withinthe substrate 102.

The top electrode 116 is coupled to an upper interconnect wire 109 u,which overlies the MRAM device 111, by way of a top electrode via 118.The top electrode via 118 is centered along a first axis 120 that isperpendicular to an upper surface 102 u of the substrate 102. The upperinterconnect wire 109 u is centered along a second axis 122 that isperpendicular to the upper surface 102 u of the substrate 102 and thatis separated from the first axis 120 by a non-zero distance 124.

The top electrode via 118 has a bottom surface with a first width w₁.The first width w₁ is less than a width w_(TE) of the top electrode 116.For example, the 1^(st) width w₁ may be less than ⅓ the width w_(TE) ofthe top electrode 116. In some embodiments, the first width w₁ may alsobe less than a width w_(BEVA) of a bottom surface of the bottomelectrode via 110. In some embodiments, the first width w₁ of the topelectrode via 118 is smaller than a minimum feature size of a photomaskused in a photolithography system (e.g., a photolithography system using193 nm illumination) to form the top electrode via 118.

The smaller width of the bottom surface of the top electrode via 118allows for the top electrode via 118 to more easily land on the topelectrode 116 during fabrication of the MRAM device 111, therebypreventing over-etching that can cause damage to the MRAM device 111.

FIGS. 2A-2B illustrate some additional embodiments of an integrated chiphaving an MRAM cell comprising a top electrode via with a smaller widththan an underlying bottom electrode via.

As shown in cross-sectional view 200 of FIG. 2A, the integrated chipcomprises a substrate 102 including an embedded memory region 202 and alogic region 204. A dielectric structure 104 is arranged over thesubstrate 102. The dielectric structure 104 comprises a plurality ofstacked inter-level dielectric (ILD) layers 206 a-206 c verticallyseparated by etch stop layers 208. In some embodiments, the plurality ofstacked ILD layers 206 a-206 c may comprise one or more of silicondioxide, SiCOH, a fluorosilicate glass, a phosphate glass (e.g.,borophosphate silicate glass), or the like. In some embodiments, theetch stop layers 208 may comprise a nitride (e.g., silicon nitride), acarbide (e.g., silicon carbide), or the like.

Within the embedded memory region 202, one or more lower interconnectlayers 106 are disposed within one or more lower ILD layers 206 a-206 b.The one or more lower interconnect layers 106 are coupled to an accessdevice 103 arranged within the substrate 102 and to a bottom electrodevia 110 arranged within the dielectric structure 104. The bottomelectrode via 110 couples the one or more lower interconnect layers 106to an MRAM device 111 surrounded by the dielectric structure 104. Insome embodiments, the access device 103 may comprise a transistor device(e.g., a MOSFET, a bi-polar junction transistor (BJT), a high electronmobility transistor (HEMT), or the like). In some embodiments, one ormore lower interconnect layers 106 may comprise copper, aluminum, or thelike. In some embodiments, the bottom electrode via 110 may comprise aliner 110 a (e.g., a glue layer and/or a diffusion barrier layer) and aconductive material 110 b. In some embodiments, the liner 110 a maycomprise tantalum nitride, titanium nitride, or the like. In someembodiments, the conductive material 110 b may comprise titanium,tantalum, tantalum nitride, titanium nitride, or the like.

The MRAM device 111 comprises a magnetic tunnel junction (MTJ) 114disposed between a bottom electrode 112 and a top electrode 116. Thebottom electrode 112 is disposed over the bottom electrode via 110. Insome embodiments, the bottom electrode 112 and the top electrode 116 maycomprise tantalum, tantalum nitride, titanium, titanium nitride, or thelike. In some embodiments, the top electrode 116 may have a width thatis in a range of between approximately 50 nm and approximately 100 nm.

The MTJ 114 includes a lower ferromagnetic layer 114 a and an upperferromagnetic layer 114 c, which are separated from one another by atunneling barrier layer 114 b. In some embodiments, the lowerferromagnetic layer 114 a may comprise a pinned layer having amagnetization that is fixed, while the upper ferromagnetic layer 114 cmay comprise a free layer having a magnetization that can changed to beeither parallel (P state) or anti-parallel (AP state) with respect tothe magnetization of pinned layer. In some embodiments, the lowerferromagnetic layer 114 a and the upper ferromagnetic layer 114 c maycomprise iron, cobalt, nickel, iron cobalt, nickel cobalt, cobalt ironboride, iron boride, iron platinum, iron palladium, or the like. In someembodiments, the tunneling barrier layer 114 b may comprise magnesiumoxide (MgO), aluminum oxide (e.g., Al₂O₃), nickel oxide, gadoliniumoxide, tantalum oxide, molybdenum oxide, titanium oxide, tungsten oxide,or the like.

In some embodiments, a lower insulating structure 210 may be disposedover the one or more lower ILD layers 206 a-206 b. The lower insulatingstructure 210 comprises sidewalls defining an opening between the bottomelectrode 112 and the one or more lower interconnect layers 106. Thebottom electrode via 110 extends through the opening in the lowerinsulating structure 210. In various embodiments, the lower insulatingstructure 210 may comprise one or more of silicon nitride, silicondioxide, silicon carbide, Tetraethyl orthosilicate (TEOS), or the like.

Sidewall spacer 214 are disposed along opposing sides of the MTJ 114 andthe top electrode 116. The sidewalls spacers 214 may have curvedoutermost sidewalls facing away from the MTJ 114. In variousembodiments, the sidewalls spacers 214 may comprise silicon nitride, asilicon dioxide (SiO₂), silicon oxy-nitride (e.g., SiON), or the like.In some embodiments, a mask layer 216 may be disposed over the topelectrode 116 and the sidewall spacers 214. In some embodiments, themask layer 216 may have a thickness in a range of between approximately100 angstroms and approximately 400 angstroms. In various embodiments,the mask layer 216 may comprise silicon nitride, a silicon dioxide(SiO₂), silicon oxy-nitride (e.g., SiON), silicon carbide, or the like.An upper ILD layer 206 c is disposed over the lower insulating structure210 and surrounds the MRAM device 111.

A top electrode via 118 is disposed within the upper ILD layer 206 c andextends through the mask layer 216 to contact the top electrode 116. Thetop electrode via 118 couples the top electrode 116 to an upperinterconnect wire 109 u. The top electrode via 118 is disposed directlyon the top electrode 116. In some embodiments, the top electrode via 118may comprise aluminum, copper, tungsten, or the like. In someembodiments, the top electrode via 118 may comprise a same material asthe upper interconnect wire 109 u.

In some embodiments, the top electrode via 118 has a bottom surface witha first width w₁. In some embodiments, the first width w₁ may be in arange of between approximately 25 nm and approximately 40 nm. In someadditional embodiments, the first width w₁ may be in a range of betweenapproximately 10 nm and approximately 30 nm. In some embodiments, abottom of the upper interconnect wire 109 u has a width that is betweenapproximately 3 and approximately 5 times larger than the first widthw₁. For example, in some embodiments the bottom of the upperinterconnect wire 109 u has a width that is in a range of betweenapproximately 70 nm and approximately 120 nm. In some additionalembodiments, the bottom of the upper interconnect wire 109 u has a widththat is approximately equal to 105 nm. The relatively small size of thefirst width wi allows for the top electrode via 118 to more easily landon the top electrode 116 during fabrication of the MRAM device 111 andprevents over-etching that can cause damage to the MRAM device 111.

Within the logic region 204, one or more additional interconnect layersare disposed within the dielectric structure 104. The one or moreadditional interconnect layers comprise a conductive contact 107L, aninterconnect via 108L, and an interconnect wire 109L. The one or moreadditional interconnect layers are coupled to a logic device 218arranged within the substrate 102. In some embodiments, the logic device218 may comprise a transistor device (e.g., a MOSFET, a bi-polarjunction transistor (BJT), a high electron mobility transistor (HEMT),or the like).

A horizontal plane 220 that is parallel to an upper surface of thesubstrate 102 extends through sidewalls of the top electrode via 118 andthrough an interconnect via 108L within the logic region 204. In someembodiments, the interconnect via 108L may extend through the lowerinsulating structure 210. The interconnect via 108L has a second widthw₂ that is larger than the first width w₁. In some embodiments, thesecond width w₂ may be in a range of between approximately 50 nm andapproximately 90 nm. In some embodiments, the first width w₁ may bebetween approximately ¼ and ¾ the second width w₂.

FIG. 2B illustrates a top-view 222 shown along line A-A′ ofcross-sectional view 200 of FIG. 2A.

As shown in top-view 222 of FIG. 2B, within the embedded memory region202 the top electrode via 118 has an elongated shape that extends alonga first direction 224 for the first width w₁ and that further extendsalong a second direction 226 for a first length L₁ that is greater thanthe first width w₁. In some embodiments, the elongated shape of the topelectrode via 118 may be oval shaped when viewed from the top-view 222.In some embodiments, the first length L₁ is in a range of betweenapproximately 150% and approximately 300% larger than the first widthwi. The first width w₁ and the first length L₁ cause the top electrodevia 118 to have a first area when viewed from the top-view 222.

Within the logic region 204, the interconnect via 108L has a shape thatis substantially symmetric about the first direction 224 and the seconddirection 226. The interconnect via 108L extends along the firstdirection 224 for the second width w₂ and further extends along thesecond direction 226 for a second length L₂ that is substantially equalto the second width w₂. In some embodiments, the interconnect via 108Lhas a substantially circular shape when viewed from the top-view 222. Insome embodiments, the second length L₂ may be approximately equal to thefirst length L₁. In other embodiments, the second length L₂ may besmaller than the first length L₁. The second width w₂ and the secondlength L₂ cause the interconnect via 108L to have a second area whenviewed from the top-view 222.

FIG. 3 illustrate some embodiments of an integrated chip 300 having anMRAM cell comprising a top electrode via with a width that is smallerthan a width of an underlying top electrode.

The integrated chip 300 comprises an MRAM device 111 disposed within adielectric structure 104 arranged over a substrate 102. The dielectricstructure 104 comprises a plurality of stacked inter-level dielectric(ILD) layers 206 a-206 c vertically separated by etch stop layers 208.One or more lower interconnect layers 106 are arranged within thedielectric structure 104. The one or more lower interconnect layers 106comprise an interconnect wire 109 having a first conductive material 302surrounded by a first liner 304 that separates the first conductivematerial 302 from the dielectric structure 104. In some embodiments, thefirst conductive material 302 may comprise tungsten, aluminum, copper,or the like. In some embodiments, the first liner 304 may comprise adiffusion barrier. In some embodiments, the first liner 304 may comprisea refractive metal or a refractive metal oxide, such as titanium,titanium-nitride, tantalum, tantalum-nitride, or the like.

The one or more lower interconnect layers 106 couple an access device103 to a bottom electrode via 110 contacting an MRAM device 111. TheMRAM device 111 comprises a bottom electrode 112 separated from a topelectrode 116 by way of an MTJ 114. In some embodiments, the topelectrode 116 may have a curved upper surface 116 u facing away from thesubstrate 102. In some embodiments, the one or more lower interconnectlayers 106 may further comprise a dummy structure 320 disposed atlocations laterally between adjacent MRAM devices. The dummy structure320 may have a smaller height than the interconnect wire 109. The dummystructure 320 enable a photolithography process to form lowerinterconnect wires at a small pitch. A lower insulating structure 210continuously extends over the dummy structure 320.

A top electrode via 118 contacts the top electrode 116. The topelectrode via 118 is further coupled to an upper interconnect wire 109 uthat is over the top electrode via 118. The top electrode via 118 andthe upper interconnect wire 109 u respectively comprise a secondconductive material 306 surrounded by a second liner 308 that separatesthe second conductive material 306 from the dielectric structure 104.The top electrode via 118 has a cross-sectional profile that isasymmetric about a line 310 bisecting the top electrode via 118. In someembodiments, the top electrode via 118 has a curved sidewall 312 thatopposes a substantially linear sidewall 314. The curved sidewall 312 hasa slope that decreases as a distance from the top electrode 116increases. In some embodiments, the curved sidewall 312 may extend alonga line 316 that is oriented at an angle θ of less than approximately 30°with respect to a horizontal plane that is parallel to an upper surfaceof the substrate 102. In some embodiments, the line 316 is oriented atan angle θ that is between approximately 10° and approximately 30°.

In some embodiments, a bottommost surface 318 of the top electrode via118 contacts the top electrode 116 at a position that is below a top ofthe top electrode 116. In some such embodiments, the top electrode via118 may extend into a recess that is within the curved upper surface 116u of the top electrode 116 and that is defined by interior surfaces ofthe top electrode 116. In some embodiments, the top electrode 116 has across-sectional profile that is asymmetric about a line (not shown)bisecting the top electrode 116. In some embodiments (not shown), due tomisalignment errors the bottommost surface 318 of the top electrode via118 contacts the top electrode 116 and sidewall spacers 214 surroundingthe top electrode 116. In some embodiments, the bottommost surface 318of the top electrode via 118 may have an angled surface with a non-zeroslope. In some embodiments, the angled surface is closer to thesubstrate 102 directly over the sidewall spacers 214 than directly overthe top electrode 116.

FIG. 4 illustrate some additional embodiments of an integrated chip 400having an MRAM cell comprising a top electrode via with a smaller widththan an underlying bottom electrode via.

The integrated chip 400 comprises a 1T1R MRAM cell architecture havingan access device 103 connected to an MRAM device 111. The access device103 is arranged within a substrate 102. In some embodiments, the accessdevice 103 may comprise a MOSFET device having a gate electrode 103 dthat is arranged between a source region 103 a and a drain region 103 band that is separated from the substrate 102 by a gate dielectric 103 c.In other embodiments, the access device 103 may comprise a HEMT, a BJT,or the like. In some embodiments, one or more isolation structure 402may be disposed within the substrate 102 along opposing sides of theaccess device 103. In some embodiments, the one or more isolationstructures 402 may comprise shallow trench isolation (STI) structures.

A dielectric structure 104 is arranged over the substrate 102. One ormore lower interconnect layers 106 including conductive contacts 107,interconnect vias 108, and interconnect wires 109, are surrounded by thedielectric structure 104. The interconnect wires 109 include asource-line SL comprising a first interconnect wire that is electricallycoupled to the source region 103 a. The interconnect wires 109 furthercomprise a word-line WL comprising a second interconnect wire that iselectrically coupled to the gate electrode 103 d.

An MRAM device 111 is arranged within the dielectric structure 104 andcomprises a bottom electrode 112 separated from a top electrode 116 byan MTJ 114. The bottom electrode 112 is connected to the drain region103 b by the one or more lower interconnect layers 106. The topelectrode 116 is further coupled to a bit-line BL by way of a topelectrode via 118 and an upper interconnect wire 109 u.

Although integrated chip 400 illustrates the word-line WL, thesource-line SL, the bit-line BL, and the MRAM device 111 as beinglocated at certain levels within a BEOL (back-end-of-the-line) stack, itwill be appreciated that the positon of these elements is not limited tothose illustrated positions. Rather, the elements may be at differentlocations within a BEOL stack. For example, in some alternativeembodiments, the MRAM device 111 may be located between a second andthird metal interconnect wire.

FIG. 5 illustrate some additional embodiments of an integrated chip 500having an MRAM cell comprising a top electrode via with a smaller widththan an underlying bottom electrode via.

The integrated chip 500 comprises a lower insulating structure 210disposed over one or more lower ILD layers 206 a-206 b. In someembodiments, the lower insulating structure 210 is separated from theone or more lower ILD layers 206 a-206 b by an etch stop layer 208. Insome embodiments, the lower insulating structure 210 comprises a firstdielectric layer 210 a, a second dielectric layer 210 b over the firstdielectric layer 210 a, and a third dielectric layer 210 c over thefirst dielectric layer 210 a and laterally abutting the seconddielectric layer 210 b. In some embodiments, the first dielectric layer210 a extends to a top of a bottom electrode via 110. In suchembodiments, a bottom electrode 112 of an MRAM device 111 may be on atop of the first dielectric layer 210 a. In some embodiments, the seconddielectric layer 210 b is completely over the bottom electrode via 110and laterally surrounds the bottom electrode 112.

In some embodiments, the first dielectric layer 210 a may comprisesilicon rich oxide or the like. In some embodiments, the firstdielectric layer 210 a may have a thickness that is in a range ofbetween approximately 150 Angstroms and approximately 200 Angstroms. Insome additional embodiments, the first dielectric layer 210 a may have athickness that is approximately equal to 180 Angstroms. In someembodiments, the first dielectric layer 210 a may have a greater (i.e.,larger) thickness in the logic region 204 than in the embedded memoryregion 202. In some embodiments, the second dielectric layer 210 b maycomprise silicon carbide, silicon nitride, or the like. In someembodiments, the second dielectric layer 210 b may be a same material asa masking layer 216 over the MRAM device 111. In some embodiments, thethird dielectric layer 210 c may comprise Tetraethyl orthosilicate(TEOS) or the like.

Within the embedded memory region 202, a first upper ILD layer 502 isdisposed over the lower insulating structure 210. The first upper ILDlayer 502 may comprise silicon dioxide, carbon doped silicon dioxide,silicon oxynitride, borosilicate glass (BSG), phosphoric silicate glass(PSG), borophosphosilicate glass (BPSG), fluorinated silicate glass(FSG), a porous dielectric material, or the like. A masking structure504 is disposed over the first upper ILD layer 502. In some embodiments,the masking structure 504 comprises a first masking layer 504 a over thefirst upper ILD layer 502 and a second masking layer 504 b over thefirst masking layer 504 a. In some embodiments, the first masking layer504 a may comprise silicon carbide, silicon nitride, or the like. Insome embodiments, the second masking layer 504 b may comprise a samematerial as the third dielectric layer 210 c. For example, in someembodiments, the second masking layer 504 b may comprise TEOS or thelike.

A second upper ILD layer 506 is disposed over the masking structure 504.The second upper ILD layer 506 laterally contacts the first upper ILDlayer 502 along an angled sidewall 502 s of the first upper ILD layer502. The second upper ILD layer 506 may comprise silicon dioxide, carbondoped silicon dioxide, silicon oxynitride, borosilicate glass (BSG),phosphoric silicate glass (PSG), borophosphosilicate glass (BPSG),fluorinated silicate glass (FSG), a porous dielectric material, or thelike. In some embodiments, the second upper ILD layer 506 comprises adifferent material than the first upper ILD layer 502.

An MRAM device 111 is surrounded by the first upper ILD layer 502. A topelectrode via 118 contacts a top of the MRAM device 111. The topelectrode via 118 extends through the second upper ILD layer 506 and apart of the masking structure 504. In some embodiments, the topelectrode via 118 may have a top that is substantially aligned with atop of the first masking layer 504 a. In some embodiments, the topelectrode via 118 has a curved sidewall that has a first curvaturedefined by a first radius R centered at a point that is a distance dabove a bottom of a bottom electrode via 110 underlying the MRAM device111.

FIG. 6 illustrates a cross-sectional view of some additional embodimentsof an integrated chip 600 having an MRAM device with a top electrode viahaving a smaller width than an underlying bottom electrode via.

The integrated chip 600 comprises an MRAM device 111 disposed over abottom electrode via 110 over a substrate 102. The MRAM device 111comprises a bottom electrode 112 separated from a top electrode 116 byan MTJ 114. A top electrode via 118 contacts the top electrode 116. Insome embodiments, the top electrode via 118 may extend to a non-zerodistance 602 below a top surface of the top electrode 116. In someembodiments, the non-zero distance 602 may be in a range of betweenapproximately 10 Angstroms and approximately 50 Angstroms. In someembodiments, the top electrode via 118 may have a bottommost surfacewith a bottom width 604 in a range of between approximately 10nanometers and approximately 30 nanometers. In some embodiments, a topof the top electrode via 118 may have a top width 606 in a range ofbetween approximately 70 nanometers and approximately 120 nanometers. Insome embodiments, a top of the bottom electrode via 110 may have a topsurface with a width 608 in a range of between approximately 60nanometers and approximately 110 nanometers.

In some embodiments, the top electrode via 118 may comprise a lowersegment 610, a middle segment 612 over the lower segment 610, and anupper segment 614 over the middle segment 612. A first line 610 a istangent to a first sidewall of the lower segment 610 of the topelectrode via 118. In some embodiments, the first line 610 a may bearranged at a first angle α with respect to a horizontal plane that isparallel to an upper surface of the substrate 102. In some embodiments,the first angle α may be approximately equal to 72°.

In some embodiments, a second line 612 a is tangent to a second sidewallof the middle segment 612 of the top electrode via 118. In someembodiments, the second line 612 a may be arranged at a second angle βwith respect to a horizontal plane that is parallel to the upper surfaceof the substrate 102. In some embodiments, the second angle β may besmaller than the first angle α. In some embodiments, the second angle βmay be approximately equal to 43°.

In some embodiments, a third line 614 a is tangent to a third sidewallof the upper segment 614 of the top electrode via 118. In someembodiments, the third line 614 a may be arranged at a third angle γwith respect to a horizontal plane that is parallel to the upper surfaceof the substrate 102. In some embodiments, the third angle γ may besmaller than the second angle β. In some embodiments, the third angle γmay be approximately equal to 13°.

In some embodiments, a fourth sidewall of the top electrode via 118opposes the first sidewall, the second sidewall, and the third sidewall.In some embodiments, the fourth sidewall may be arranged at a fourthangle δ with respect to a horizontal plane that is parallel to the uppersurface of the substrate 102. In some embodiments, the fourth angle δmay be larger than the first angle α. In some embodiments, the fourthangle δ may be approximately equal to 83°.

FIGS. 7-25 illustrate cross-sectional views 700-2500 of some embodimentsof a method of forming an integrated chip having an MRAM cell comprisinga top electrode via with a smaller width than an underlying bottomelectrode via. Although FIGS. 7-25 are described in relation to amethod, it will be appreciated that the structures disclosed in FIGS.7-25 are not limited to such a method, but instead may stand alone asstructures independent of the method.

As shown in cross-sectional view 700 of FIG. 7, an access device 103 isformed within a substrate 102. In various embodiments, the substrate 102may be any type of semiconductor body (e.g., silicon, SiGe, SOI, etc.),such as a semiconductor wafer and/or one or more die on a wafer, as wellas any other type of semiconductor and/or epitaxial layers, associatedtherewith. In some embodiments, the access device 103 may comprise atransistor formed by depositing a gate dielectric film and a gateelectrode film over the substrate 102. The gate dielectric film and thegate electrode film are subsequently patterned to form a gate dielectric103 c and a gate electrode 103 d. The substrate 102 may be subsequentlyimplanted to form a source region 103 a and a drain region 103 b withinthe substrate 102 on opposing sides of the gate electrode 103d.

In some embodiments, one or more isolation structures 402 may be formedwithin the substrate 102 on opposing sides of the access device 103. Insome embodiments, the one or more isolation structures 402 may be formedby selectively etching the substrate 102 to form one or more shallowtrenches 702 and subsequently forming one or more dielectric materialswithin the one or more shallow trenches 702. In some embodiments, theetching process may comprise a dry etching process. For example, theetching process may comprise a plasma etching process, such as aninductively coupled plasma (ICP) etching process, a capacitively coupledplasma (CCP) etching process, or the like. In other embodiments, theetching process may comprise a wet etching process.

As shown in cross-sectional view 800 of FIG. 8, one or more lowerinterconnect layers 106 are formed within one or more lower inter-leveldielectric (ILD) layers 206 a-206 b over the substrate 102. The one ormore lower interconnect layers 106 may be formed by forming one of theone or more lower ILD layers 206 a-206 b over the substrate 102,selectively etching the ILD layer (e.g., an oxide, a low-k dielectric,or an ultra low-k dielectric) to define a via hole and/or a trenchwithin the ILD layer, forming a conductive material (e.g., copper,aluminum, etc.) within the via hole and/or a trench to fill the opening,and performing a planarization process (e.g., a chemical mechanicalplanarization process).

As shown in cross-sectional view 900 of FIG. 9, a first dielectric layer210 a is formed onto the one or more lower interconnect layers 106 andthe one or more lower ILD layers 206 a-206 b. In some embodiments, thefirst dielectric layer 210 a may comprise one or more ofsilicon-nitride, silicon-carbide, or the like. In some embodiments, thefirst dielectric layer 210 a may be formed by a plurality of differentdeposition processes (e.g., physical vapor deposition (PVD), chemicalvapor deposition (CVD), PE-CVD, atomic layer deposition (ALD),sputtering, etc.) to a thickness in a range of between approximately 200angstroms and approximately 300 angstroms. After deposition, the firstdielectric layer 210 a is selectively patterned to define an opening 902extending through the first dielectric layer 210 a to the one or morelower interconnect layers 106.

In some embodiments, a bottom electrode via 110 is formed within theopening 902. In some embodiments, the bottom electrode via 110 may beformed by forming liner 110 a within the opening 902. In variousembodiments, the liner 110 a may comprise a glue layer configured toincrease adhesion between adjacent layers and/or a diffusion barrierlayer configured to prevent diffusion between adjacent layers. Aconductive material 110 b is formed over the liner 110 a within theopening 902. In some embodiments, the liner 110 a and the conductivematerial 110 b may be formed by deposition processes. A planarizationprocess (e.g., a chemical mechanical planarization process) maysubsequently be performed. In some embodiments, the liner 110 a maycomprise tantalum nitride, titanium nitride, or the like. In someembodiments, the conductive material 110 b may comprise tantalum,titanium, or the like.

As shown in cross-sectional view 1000 of FIG. 10, a bottom electrodelayer 1002 is formed on the first dielectric layer 210 a and theconductive material 110 b. A lower ferromagnetic electrode 1004, atunneling barrier layer 1006, an upper ferromagnetic electrode 1008, anda top electrode layer 1010 are subsequently formed over the bottomelectrode layer 1002.

As shown in cross-sectional view 1100 of FIG. 11, one or more patterningprocesses are performed to define an MRAM device 111. In someembodiments, a first patterning process comprises a first etchingprocess of the lower ferromagnetic electrode (1004 of FIG. 10), thetunneling barrier layer (1006 of FIG. 10), the upper ferromagneticelectrode (1008 of FIG. 10), and the top electrode layer (1010 of FIG.10). The first etching process defines a lower ferromagnetic layer 114a, an upper ferromagnetic layer 114 c, a tunneling barrier layer 114 b,and a top electrode 116.

After the first patterning process, sidewall spacers 214 may be formedalong opposing sides of the top electrode 116. In some embodiments, thesidewall spacers 214 may be formed by depositing a spacer layer over thesubstrate 102 using a deposition technique (e.g., PVD, CVD, PE-CVD, ALD,sputtering, etc.). The spacer layer is subsequently etched to remove thespacer layer from horizontal surfaces, leaving the spacer layer alongopposing sides of the top electrode 118 as the sidewall spacers 214. Invarious embodiments, the spacer layer may comprise silicon nitride, asilicon dioxide (SiO₂), silicon oxy-nitride (e.g., SiON), or the like.In various embodiments, the spacer layer may be formed to a thickness ina range of between approximately 400 Angstroms and approximately 600Angstroms. A second etching process is subsequently performed to removeparts of the bottom electrode layer 1002 and to define a bottomelectrode 112.

After the second etching process, a masking layer 216 may be formed overthe MRAM device 111 and a second dielectric 1102 may be formed over thefirst dielectric layer 210 a. In some embodiments, the masking layer 216and the second dielectric 1102 may comprise a same material and/or beconcurrently formed. For example, the masking layer 216 and the seconddielectric 1102 may comprise silicon carbide, silicon nitride, or thelike. In some embodiments (not shown), the material of the masking layer216 may be formed along sidewalls of the sidewall spacers 214. In suchembodiments, a thickness of the material along the sidewalls of thesidewall spacers 214 is much less than (e.g., 1 to 4 orders ofmagnitude) that of the masking layer 216 or the second dielectric 1102.

As shown in cross-sectional view 1200 of FIG. 12, a first upper ILDlayer 1202 is formed over the second dielectric 1102. The first upperILD layer 1202 is formed to cover the MRAM device 111. In someembodiments, the first upper ILD layer 1202 may be deposited by adeposition process (e.g., PVD, CVD, PE-CVD, ALD, or the like). Invarious embodiments, the first upper ILD layer 1202 may comprise silicondioxide, carbon doped silicon dioxide, silicon oxynitride, borosilicateglass (BSG), phosphoric silicate glass (PSG), borophosphosilicate glass(BPSG), fluorinated silicate glass (FSG), a porous dielectric material,or the like. In some embodiments, the first upper ILD layer 1202 may beformed to a thickness of between approximately 50 nm and approximately175 nm.

As shown in cross-sectional view 1300 of FIG. 13, a first masking layer504 a is formed over the first upper ILD layer (1202 of FIG. 12) withinthe embedded memory region 202. The first upper ILD layer (1202 of FIG.12) is subsequently etched according to the first masking layer 504 a toremove the first upper ILD layer (1202 of FIG. 12) from within the logicregion 204. The etching process causes the first upper ILD layer 502 tohave an angled sidewall 502 s facing the logic region 204. In someembodiments, the first masking layer 504 a may be deposited by way ofone or more deposition processes followed by a photolithographicpatterning process. In various embodiments, the first masking layer 504a may comprise one or more of silicon carbide, silicon nitride, or thelike. In some embodiments, the layer of silicon carbide may have athickness in a range of between approximately 100 Angstroms andapproximately 200 Angstroms. In some additional embodiments, the layerof silicon carbide may have a thickness that is approximately equal to150 Angstroms.

A second masking layer 504 b and a third dielectric layer 210 c areformed over the substrate 102 after the etching process is completed.The second masking layer 504 b may be formed on the first masking layer504 a and the third dielectric layer 210 c may be formed onto the firstdielectric layer 210 a. In some embodiments, the second masking layer504 b and the third dielectric layer 210 c may be a same material and/orbe concurrently formed. For example, the second masking layer 504 b andthe third dielectric layer 210 c may comprise TEOS or the like. In someembodiments (not shown), a material of the second masking layer 504 bmay be formed along the angled sidewall 502 s. In such embodiments, athickness of the material along the angled sidewall 502 s is much lessthan (e.g., 1 to 3 orders of magnitude) that of the second masking layer504 b and the third dielectric layer 210 c due to the anisotropy of aprocess used to form the material.

As shown in cross-sectional view 1400 of FIG. 14, a second upper ILDlayer 506 is formed over the lower insulating structure 210. The secondupper ILD layer 506 covers the first upper ILD layer 502. In someembodiments, the second upper ILD layer 506 may be deposited by adeposition process. In various embodiments, the second upper ILD layer506 may comprise silicon dioxide, carbon doped silicon dioxide, siliconoxynitride, borosilicate glass (BSG), phosphoric silicate glass (PSG),borophosphosilicate glass (BPSG), fluorinated silicate glass (FSG), aporous dielectric material, or the like. In some embodiments, the secondupper ILD layer 506 may be formed to a thickness of betweenapproximately 100 nm and approximately 200 nm. In some embodiments, thesecond upper ILD layer 506 may be formed to a thickness of approximately160 nm.

As shown in cross-sectional view 1500 of FIG. 15, a hard mask structure1501 is formed over the second upper ILD layer 506. In some embodiments,the hard mask structure 1501 may comprise a multilayer hard maskstructure. In some embodiments, the hard mask structure 1501 comprises alower hard mask layer 1502 and an upper hard mask layer 1504. In someembodiments, the lower hard mask layer 1502 may comprise a dielectrichard mask layer and/or an antireflective coating. For example, in someembodiments, the lower hard mask layer 1502 may comprise a dielectrichard mask layer (e.g., an oxide) and a nitrogen free anti-reflectivelayer (NFARL) over the dielectric hard mask layer. In some suchembodiments, the dielectric hard mask layer may comprise a dielectricmaterial having a thickness in a range of between approximately 50Angstroms and approximately 150 Angstroms and the NFARL may have athickness in a range of between approximately 150 Angstroms andapproximately 250 Angstroms. In some additional embodiments, thedielectric hard mask layer may have a thickness that is approximatelyequal to 100 Angstroms and the NFARL may have a thickness ofapproximately 200 Angstroms. The upper hard mask layer 1504 may comprisea metal, such as titanium, tantalum, or the like. In some suchembodiments, the upper hard mask layer 1504 may have a thickness in arange of between approximately 250 Angstroms and approximately 500Angstroms. In some additional embodiments, the upper hard mask layer1504 may have a thickness that is approximately equal to 350 Angstroms.

A first patterning structure 1503 is formed over the hard mask structure1501. The first patterning structure 1503 has sidewalls that define afirst opening 1510 a within the embedded memory region 202 and a secondopening 1510 b within the logic region 204. In some embodiments, thefirst patterning structure 1503 comprises a tri-layer photoresist. Insome such embodiments, the first patterning structure 1503 may compriseone or more planarizing layers 1506 and an overlying photoresist layer1508. In some embodiments, the one or more planarizing layers 1506comprise one or more of a silicon containing hard-mask, an oxide, anorganic material, a spin on carbon (SOC), or the like.

As shown in cross-sectional view 1600 of FIG. 16, the hard maskstructure 1501 is patterned according to the first opening 1510 a andthe second opening 1510 b to respectively define a third opening 1602 awithin the embedded memory region 202 and a fourth opening 1602 b withinthe logic region 204. The third opening 1602 a is centered along avertically extending first line 1604 that is offset from a verticallyextending second line 1606 that is centered on the MRAM device 111. Insome embodiments, the first line 1604 is offset from the second line1606 by a first non-zero distance 1608. In some embodiments, the firstnon-zero distance 1608 may be in a range of between approximately 30 nmand approximately 55 nm. In some embodiments, the first non-zerodistance 1608 may be approximately equal to 45 nm.

As shown in cross-sectional view 1700 of FIG. 17A, a second patterningstructure 1701 is formed over the hard mask structure 1501. The secondpatterning structure 1701 has sidewalls that define a fifth opening 1706over the third opening 1602 a. The fifth opening 1706 is defined by afirst sidewall of the second patterning structure 1701 that is directlyover the third opening 1602 a and a second sidewall of the secondpatterning structure 1701 that is outside of the third opening 1602 a.In some embodiments, the second sidewall is directly over the upper hardmask layer 1504. In such embodiments, the fifth opening 1706continuously extends in opposing directions past a sidewall of the upperhard mask layer 1504 that defines the third opening 1602 a, while thethird opening 1602 a continuously extends past a sidewall of the secondpatterning structure 1701 that defines the fifth opening 1706. In someembodiments, the fifth opening 1706 is centered along a verticallyextending second line 1708 that is offset from the first line 1604 by asecond non-zero distance 1709. In some embodiments, the second line 1708is substantially aligned (e.g., within a CD tolerance of less thanapproximately 5 nm) with a vertical line bisecting the MRAM device 111.

In some embodiments, the fifth opening 1706 may have a width that is ina range of between approximately 60 nm and approximately 80 nm. Anintersection of the third opening 1602 a and the fifth opening 1706define a top electrode via region 1710 (i.e., a region in which the topelectrode via will be subsequently formed) having a smaller width thanthe fifth opening 1706. In some embodiments, the top electrode viaregion 1710 may have a width that is between approximately ¼ andapproximately ½ of the width of the fifth opening 1706.

In some embodiments, the second patterning structure 1701 comprises atri-layer photoresist. In some such embodiments, the second patterningstructure 1701 may comprise one or more planarizing layers 1702 and aphotoresist layer 1704. In some embodiments, the one or more planarizinglayers 1702 comprise one or more of a silicon containing hard-mask, anoxide, an organic material, a spin on carbon (SOC), or the like. In suchembodiments, the width of the fifth opening 1706 is an after developmentinspection (ADI) width (a width of the opening within the photoresistlayer 1704 occurring after development of the photoresist layer 1704).

FIG. 17B illustrates a top-view 1712 of the cross-sectional view 1700 ofFIG. 17A (taken along line A-A′). As shown in top-view 1712, anintersection of the third opening 1602 a and the fifth opening 1706define the top electrode via region 1710, which has a smaller area thanthe fifth opening 1706.

As shown in cross-sectional view 1800 of FIG. 18A, a first etchingprocess is performed according the second patterning structure (1701 ofFIG. 17A) to define a top electrode via hole 1802. The top electrode viahole 1802 extends through the second upper ILD layer 506 to the MRAMdevice 111. The hard mask structure 1501 limits an area of the secondupper ILD layer 506 that the first etch process etches, so as to providefor a top electrode via hole 1802 that has a bottom with a first widthw₁ (e.g., an after etch inspection (AEI) width) that is smaller than awidth of the fifth opening (1706 of FIG. 17). The first width w₁ of thebottom of the top electrode via hole 1802 makes it easier to form thevia directly over the MRAM device 111 and also reduces over-etching(since the smaller size of the top electrode via hole 1802 allows lessetchant into the hole and thus reduces over-etching). In someembodiments, the first width wi is in a range of between approximately10 nm and approximately 30 nm. In some embodiments, the first width wimay be approximately equal to 25 nm. FIG. 18B illustrates a top-view1806 (taken along line A-A′) of the cross-sectional view 1800 of FIG.18A.

In some embodiments, the etching process will extend to different depthsin different regions. For example, in regions directly below both thethird opening (1602 a of FIG. 17A) and the fifth opening (1706 of FIG.17A), the etching process forms the top electrode via hole 1802 thatextends to the MRAM device 111. In regions directly below the thirdopening (1602 a of FIG. 17A) and not below the fifth opening (1706 ofFIG. 17A), the etching process exposes an upper surface of the lowerhard mask layer 1502. In regions directly below the fifth opening (1706of FIG. 17A) and not below the third opening (1602 a of FIG. 17A),etching process removes a part of the upper hard mask layer 1504 to forman upper surface 1804 of the upper hard mask layer 1504 that is below atop of the upper hard mask layer 1504.

As shown in cross-sectional view 1900 of FIG. 19A, a third patterningstructure 1901 is formed over the hard mask structure 1501. In someembodiments, the third patterning structure 1901 may comprise atri-layer photoresist having one or more planarizing layers 1902 and aphotoresist layer 1904 over the one or more planarizing layers 1902. Thethird patterning structure 1901 comprises sidewalls defining a sixthopening 1906 directly over the fourth opening 1602 b within the hardmask structure 1501. The sidewalls of the third patterning structure1901 are directly over the fourth opening 1602 b. In some embodiments,the sixth opening 1906 may have a width that is approximately equal to awidth of the fifth opening (1706 of FIG. 17A). FIG. 19B illustrates atop-view 1908 of the cross-sectional view 1900 of FIG. 19A (taken alongline A-A′).

As shown in cross-sectional view 2000 of FIG. 20, a second etchingprocess is performed according to the third patterning structure 1901 todefine a via hole 2002. The via hole 2002 extends through the secondupper ILD layer 506 to the lower insulating structure 210. In someembodiments, the via hole 2002 may have a second width w₂ that is in arange of between approximately 40 nm and approximately 60 nm. In someembodiments, the second width w₂ may be approximately equal to 45 nm.

As shown in cross-sectional view 2100 of FIG. 21A, the third patterningstructure (1901 of FIG. 20) is removed. In some embodiments, the thirdpatterning structure may be removed by a plasma stripping/ashingprocess. FIG. 21B illustrates a top-view 2102 of the cross-sectionalview 2100 of FIG. 21A.

As shown in cross-sectional view 2200 of FIG. 22, a third etchingprocess is performed to define a first interconnect trench 2202 a withinthe embedded memory region 202 and a second interconnect trench 2202 bwithin the logic region 204. In some embodiments, the third etchingprocess removes parts of the lower hard mask layer 1502 that are notcovered by the upper hard mask layer 1504. The fifth etching processcauses the top electrode via hole 1802 to be aligned with a firstsidewall of the second upper ILD layer 506 defining the firstinterconnect trench 2202 a and to be misaligned with an opposing secondsidewall of the second upper ILD layer 506 defining the firstinterconnect trench 2202 a. The via hole 2002 is substantially centeredwith the second interconnect trench 2202 b.

As shown in cross-sectional view 2300 of FIG. 23, a wet etching processis performed on the first upper ILD layer 502 and on the second upperILD layer 506. The wet etching process removes residue and/orcontaminants remaining after completion of the third etching process.The wet etching process may also remove parts of the first upper ILDlayer 502 and the second upper ILD layer 506 that were damaged by thethird etching process (e.g., by plasma damage). The wet etching processdecreases slopes (i.e., increases an angle of the sidewalls relative toa vertical line) of sidewalls of the first upper ILD layer 502 and thesecond upper ILD layer 506. In some embodiments, the wet etching processmay cause the top electrode via hole 1802 to extend a non-zero distance602 below a top of a top electrode 116 within the MRAM device 111.

As shown in cross-sectional view 2400 of FIG. 24, a conductive material2402 is formed within the top electrode via hole 1802, the via hole2002, the first interconnect trench 2202 a, and the second interconnecttrench 2202 b. The conductive material 2402 fills the top electrode viahole 1802, the via hole 2002, the first interconnect trench 2202 a, andthe second interconnect trench 2202 b. In some embodiments, theconductive material may be deposited by a physical vapor depositiontechnique (e.g., PVD, CVD, PE-CVD, ALD, etc.) and a subsequent platingprocess (e.g., electroplating, electro-less plating, etc.). In variousembodiments, the conductive material may comprise tungsten, copper, oraluminum copper, for example.

As shown in cross-sectional view 2500 of FIG. 25, a planarizationprocess is performed. The planarization process removes excess of theconductive material (2402 of FIG. 24) from over the second upper ILDlayer 506 to define an upper interconnect wire 109 u. In someembodiments, the planarization process may also remove the hard maskstructure (1501 of FIG. 24). In some embodiments, the planarizationprocess may comprise a chemical mechanical planarization (CMP) process.

As shown in cross-sectional view 2600 of FIG. 26, one or more additionalinterconnect layers 2602 are formed over the upper interconnect wire 109u. In some embodiments, the one or more additional interconnect layers2602 be formed by way of a damascene process. In such embodiments, anadditional ILD layer 2604 is formed over the second upper ILD layer 506.The additional ILD layer 2604 is subsequently etched to form a via holeand/or trench, which is filled with a conductive material (e.g.,tungsten, copper, and/or aluminum). A chemical mechanical planarization(CMP) process is subsequently performed to remove excess of theconductive material from over the additional ILD layer 2604.

FIG. 27 illustrates a flow diagram of some embodiments of a method 2700of forming an integrated chip having an MRAM cell comprising a topelectrode via having a smaller width than an underlying bottom electrodevia.

While method 2700 is illustrated and described herein as a series ofacts or events, it will be appreciated that the illustrated ordering ofsuch acts or events are not to be interpreted in a limiting sense. Forexample, some acts may occur in different orders and/or concurrentlywith other acts or events apart from those illustrated and/or describedherein. In addition, not all illustrated acts may be required toimplement one or more aspects or embodiments of the description herein.Further, one or more of the acts depicted herein may be carried out inone or more separate acts and/or phases.

At 2702, an access device is formed within a substrate. FIG. 7illustrates a cross-sectional view 700 of some embodiments correspondingto act 2702.

At 2704, one or more lower interconnect layers are formed over thesubstrate. FIG. 8 illustrates a cross-sectional view 800 of someembodiments corresponding to act 2704.

At 2706, an MRAM device is formed over the one or more lowerinterconnect layers. FIGS. 9-11 illustrate cross-sectional views900-1100 of some embodiments corresponding to act 2706.

At 2708, one or more upper inter-level dielectric (ILD) layers areformed over the MRAM device. FIGS. 12-14 illustrate cross-sectionalviews 1200-1400 of some embodiments corresponding to act 2708.

At 2710, one or more upper inter-level dielectric (ILD) layers arepatterned to define a top electrode via hole having first width over theMRAM device. In some embodiments, the top electrode via hole may beformed according to acts 2712-2718.

At 2712, a hard mask structure is formed over the one or more upper ILDlayers. FIG. 15 illustrates a cross-sectional view 1500 of someembodiments corresponding to act 2712.

At 2714, the hard mask structure is patterned according to a firstpatterning structure to form a first opening bisected by a first linethat is laterally offset from a second line bisecting the MRAM device.FIG. 16 illustrates a cross-sectional view 1600 of some embodimentscorresponding to act 2714.

At 2716, a second patterning structure is formed having a second openingthat laterally overlaps a sidewall of the hard mask structure definingthe first opening. FIG. 17A illustrates a cross-sectional view 1700 ofsome embodiments corresponding to act 2716.

At 2718, the one or more upper ILD layers are patterned directly belowan intersection of the first opening and the second opening to define atop electrode via hole. FIG. 18A illustrates a cross-sectional view 1800of some embodiments corresponding to act 2718.

At 2720, the one or more upper ILD layers are patterned to define a viahole having a second width, which is greater than the first width, atlocation laterally separated from the top electrode via hole. FIG.19A-21 illustrate cross-sectional views 1900-2100 of some embodimentscorresponding to act 2720.

At 2722, the one or more upper ILD layers are patterned to defineinterconnect trenches over the top electrode via hole and over the viahole. FIGS. 22-23 illustrate cross-sectional views 2200-2300 of someembodiments corresponding to act 2722.

At 2724, a conductive material is formed within the top electrode viahole, the via hole, and the interconnect trenches. FIGS. 24-25illustrate cross-sectional views 2400-2500 of some embodimentscorresponding to act 2724.

At 2726, one or more additional interconnect wires are formed inadditional ILD layers over the one or more upper ILD layers. FIG. 26illustrates a cross-sectional view 2600 of some embodimentscorresponding to act 2726.

Although method 2700 describes the formation of a top electrode via holeprior to the formation of an interconnect trench, it will be appreciatedthat in some alternative embodiments, the metal trench may be formed inthe one or more upper ILD layers prior to the formation of the topelectrode via hole. In such embodiments, an opening in a masking layerdefining an interconnect trench straddles an opening in a masking layerdefining a top electrode via hole.

Furthermore, although the disclosed figures and description aredescribed in relation to magnetic random access memory (MRAM) devices,it will be appreciated that the disclosed reactivity reducing layer isnot limited to such memory devices. Rather, in some alternativeembodiments, the disclosed top electrode via may be formed over othertypes of memory devices such as, but not limited to, phase change randomaccess memory (PCRAM), resistive random access memory (RRAM),ferroelectric random access memory (FRAM), programmable metallizationmemory, carbon nanotube memory, or the like.

Accordingly, in some embodiments, the present disclosure relates to anintegrated chip comprising an MRAM cell having a top electrode via witha size that is smaller than a minimum feature size defined by acharacteristics of a photolithography system, and an associated methodof formation.

In some embodiments, the present disclosure relates to an integratedchip. The integrated chip includes a magnetoresistive random accessmemory (MRAM) device surrounded by a dielectric structure disposed overa substrate, the MRAM device including a magnetic tunnel junctiondisposed between a bottom electrode and a top electrode; a bottomelectrode via coupling the bottom electrode to a lower interconnectwire; and a top electrode via coupling the top electrode to an upperinterconnect wire, a bottom surface of the top electrode via having afirst width that is smaller than a second width of a bottom surface ofthe bottom electrode via. In some embodiments, a first line is tangentto a first outermost sidewall of the top electrode via and a second lineis tangent to an opposing second outermost sidewall of the top electrodevia; and the first line is oriented at a first angle with respect to ahorizontal plane that is parallel to an upper surface of the substrateand the second line is oriented at a second angle with respect to thehorizontal plane, the second angle less than the first angle. In someembodiments, the bottom surface of the top electrode via has a non-zeroslope. In some embodiments, the bottom surface of the top electrode viahas an oval shape. In some embodiments, the top electrode via isasymmetric with respect to a line bisecting the top electrode via asviewed along a cross-sectional view of the top electrode via. In someembodiments, the top electrode via has a first sidewall that issubstantially linear along a cross-sectional view of the top electrodevia and an opposing sidewall that is curved along the cross-sectionalview. In some embodiments, the top electrode via is centered along afirst axis that is perpendicular to an upper surface of the substrate;and the upper interconnect wire is centered along a second axis that isperpendicular to the upper surface of the substrate and that isseparated from the first axis by a non-zero distance. In someembodiments, the bottom surface of the top electrode via has the firstwidth along a first direction and a first length along a seconddirection that is perpendicular to the first direction; and the firstlength is greater than the first width. In some embodiments, the firstlength is between approximately 150% and approximately 300% greater thanthe first width. In some embodiments, the bottom surface of the topelectrode via is below a top of the top electrode. In some embodiments,the first width of the bottom surface of the top electrode via is lessthan ⅓ a third width of the top electrode via. In some embodiments, theintegrated chip further includes a lower insulating structure laterallysurrounding the bottom electrode via; a first upper inter-leveldielectric (ILD) layer laterally surrounding the MRAM device; and asecond upper ILD layer disposed over the first upper ILD layer andlaterally contacting an angled sidewall of the first upper ILD layer,the top electrode via extends through the first upper ILD layer and theupper interconnect wire extends through the second upper ILD layer.

In other embodiments, the present disclosure relates to an integratedchip. The integrated chip includes a bottom electrode arranged over asubstrate; a magnetic tunnel junction disposed over the bottomelectrode; a top electrode disposed over the magnetic tunnel junction; atop electrode via disposed on the top electrode, the top electrode viacentered along a first axis that is perpendicular to an upper surface ofthe substrate; and an upper interconnect wire contacting a top of thetop electrode via, the upper interconnect wire centered along a secondaxis that is perpendicular to the upper surface of the substrate andthat is laterally separated from the first axis by a non-zero distance.In some embodiments, the integrated chip further includes a lowerinterconnect wire arranged within a lower ILD layer below the bottomelectrode; and a lower insulating layer arranged on the lower ILD layerand laterally surrounding a bottom electrode via coupling the lowerinterconnect wire to the bottom electrode, a bottom surface of the topelectrode via having a first width that is smaller than a second widthof the bottom electrode via. In some embodiments, the integrated chipfurther includes an additional interconnect via laterally separated fromthe magnetic tunnel junction along a horizontal plane that is parallelto the upper surface of the substrate, a bottom surface of the topelectrode via having a first width that is smaller than a second widthof a bottom surface of the additional interconnect via. In someembodiments, the top electrode via has a different shape than theadditional interconnect via when viewed from a top-view of the topelectrode via and the additional interconnect via. In some embodiments,the top electrode has interior surfaces that define a recess within acurved upper surface of the top electrode, the top electrode viacontacting one or more of the interior surfaces. In some embodiments,the top electrode via includes a conductive material surrounded by aliner.

In yet other embodiments, the present disclosure relates to a method offorming an integrated chip. The method includes forming an upper ILDlayer over an MRAM device over a substrate; forming a hard maskstructure over the upper ILD layer, the hard mask structure havingsidewalls defining a first opening that is directly over the MRAM deviceand that is centered along a first line perpendicular to an uppersurface of the substrate; forming a patterning structure over the hardmask structure, the patterning structure having sidewalls defining asecond opening that is directly over the MRAM device and that iscentered along a second line perpendicular to the upper surface of thesubstrate, the second line laterally offset from the first line by anon-zero distance; etching the upper ILD layer directly below anintersection of the first opening and the second opening to define a topelectrode via hole; and filling the top electrode via hole with aconductive material. In some embodiments, the second opening extendspast the first opening in a first direction and the first openingextends past the second opening in an opposite second direction.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. An integrated chip, comprising: a memory devicesurrounded by a dielectric structure disposed over a substrate, whereinthe memory device comprises a data storage structure disposed between abottom electrode and a top electrode; a top electrode via coupling thetop electrode to an upper interconnect wire; wherein a first line istangent to a first outermost sidewall of the top electrode via and asecond line is tangent to an opposing second outermost sidewall of thetop electrode via; and wherein the first line is oriented at a firstangle with respect to a horizontal plane that is parallel to an uppersurface of the substrate and the second line is oriented at a secondangle with respect to the horizontal plane, the second angle less thanthe first angle.
 2. The integrated chip of claim 1, wherein the secondoutermost sidewall is a curved sidewall.
 3. The integrated chip of claim1, wherein the top electrode via has a bottom surface; and wherein thetop electrode via laterally extends a first distance past a first edgeof the bottom surface and a second distance past an opposing second edgeof the bottom surface, the first distance being larger than the seconddistance.
 4. The integrated chip of claim 1, wherein the top electrodevia has a bottom surface that is centered along a vertical line, thevertical line offset from a center of the top electrode via by anon-zero distance.
 5. The integrated chip of claim 1, wherein a bottomsurface of the top electrode via extends for a first distance in a firstdirection and for a second distance in a second direction, the seconddistance larger than the first distance; and wherein the first directionand the second direction are parallel to the upper surface of thesubstrate.
 6. The integrated chip of claim 1, wherein a top of the topelectrode via is off centered from a bottom of the top electrode via. 7.The integrated chip of claim 1, wherein the top electrode via has afirst width extending from the first outermost sidewall to the secondoutermost sidewall, the first width being less than or equal toapproximately 25 nm.
 8. The integrated chip of claim 1, furthercomprising: a second via disposed within the dielectric structure andlaterally separated from the top electrode via, wherein the topelectrode via has a first width and the second via has a second widththat is larger than the first width.
 9. The integrated chip of claim 8,wherein the top electrode via has a first height and the second via hasa second height that is larger than the first height.
 10. An integratedchip, comprising: a memory device laterally surrounded by an inter-leveldielectric (ILD) layer disposed over a substrate, wherein the memorydevice comprises a data storage structure disposed between a bottomelectrode and a top electrode; and a top electrode via coupling the topelectrode to an upper interconnect wire, wherein a bottom surface of thetop electrode via has an oval shape.
 11. The integrated chip of claim10, further comprising: a second via laterally separated from the topelectrode via by the ILD layer, wherein the top electrode via has afirst width and the second via has a second width that is larger thanthe first width.
 12. The integrated chip of claim 10, furthercomprising: a second via laterally separated from the top electrode viaby the ILD layer, wherein the second via has a different shape than thetop electrode via as viewed along a top-view.
 13. The integrated chip ofclaim 10, wherein the top electrode via extends below a top of the topelectrode.
 14. The integrated chip of claim 10, wherein a top of the topelectrode via is at least twice as wide as a bottom of the top electrodevia.
 15. An integrated chip, comprising: a memory device laterallysurrounded by an inter-level dielectric (ILD) material disposed over asubstrate, wherein the memory device comprises a data storage structuredisposed between a bottom electrode and a top electrode; and a topelectrode via coupling the top electrode to an upper interconnect wire,wherein the top electrode via is asymmetric with respect to a linebisecting the top electrode via as viewed along a cross-sectional viewof the top electrode via.
 16. The integrated chip of claim 15, whereinthe top electrode via has a bottom surface; and wherein the topelectrode via laterally extends past the bottom surface in a firstdirection for a first distance and the top electrode via laterallyextends past the bottom surface in an opposing second direction for asecond distance that is larger than the first distance.
 17. Theintegrated chip of claim 15, wherein a side of the top electrode via isdefined by a slope that decreases as a distance from the top electrodeincreases.
 18. The integrated chip of claim 15, wherein a first side ofthe top electrode via has a first slope and an opposing second side ofthe top electrode via has a second slope that is greater than the firstslope.
 19. The integrated chip of claim 15, wherein a bottom of the topelectrode via is off centered from a top of the top electrode via. 20.The integrated chip of claim 15, further comprising: a second vialaterally separated from the top electrode via by the ILD material,wherein a bottom surface of the second via has a larger width than abottom surface of the top electrode via.